alt Hacker News>They are usually on a separate Network.
Then someone plugs in a cable because boss wants something "over there" and there's already a network that runs "over there". Or optimizes to a smart switch with vlans, and then someone else optimizes to a single vlan. It's not hard to not give a shit, or not understand, network security.
That someone can be brought into an office and shown a small diagram of the approved network topology. Then they can be shown a small diagram of the current network topology. Next, they can be asked if they're the same. If they're not, they can finally be asked if they're aware that deviating from the approved network topology without consulting infosec is grounds for termination of their employment.